Voltammetric peak area as instrumental datum. A possibility to improve the determination at ultratrace level concentration of platinum group metals (PGMs) and lead. Application to particulate matter

摘要

Peak area as instrumental datum for determining the concentration of metals in solution instead of peak height is proposed for analytical voltammetric determinations. In the case of species present at ultratrace concentration level or having low reversibility degree of the electrodic processes, the employment of peak area permits to achieve limits of detection lower even more of one order of magnitude. The present work shows the possibility of determining at ultratrace level concentration Pd(II), Pt(II), Rh(III) and Pb(II) by voltammetry in particulate matter; these species, linked to vehicle emissions, show to have, in the supporting electrolytes employed, a very high irreversibility degree of the electrodic processes. 0.1 mol/L HCl, 0.1 mol/L HCI + 1.8 x 10(-4) mol/L dimethylglyoxime (DMG) and 0.6 mmol/L formaldehyde + 1.2 mmol/L hydrazine (formazone complex) in 0.1 mol/L HCl were employed as the supporting electrolytes. For all the elements, the accuracy, expressed as relative error e%, and the precision as repeatability, expressed as relative standard deviation s(r) (%), were very satisfactory, being lower than 6%. To better validate the analytical procedure, a comparison with spectroscopic (graphite furnace atomic absorption spectroscopy, GFAAS) measurements is also reported.